Pendulum-type mounts used to position an elevator car in a frame which moves through the elevator hoistway are known in the prior art. An example of one such mount assembly is shown in British Pat. No. 1,407,158 published Sept. 24, 1975. The pendulum mount is desirable because it allows the car to move laterally, both linearly and torsionally within the frame as the frame vibrates during passage through the hoistway. The frame traverses the hoistway on rails via guide rollers which are mounted on the frame. The frame will vibrate during such movement because of misalignment of the tracks in the hoistway; because of steps at joints between successive sections of track; because of misalignment of the guide wheels on the frame; and the like. The frame vibrations will tend to be well defined, sharp occurrences of varying magnitude, depending on the cause, and will be transferred to the car if the car is tightly fixed to the frame. Rubber pads have been used in the past to try to minimize transfer of vibration from the frame to the car, whereby a quieter more comfortable ride is afforded the passengers on the elevator.
The pendulum mount assembly provides a means for transforming the shock-type vibrations imparted to the frame, into lateral, linear or torsional movements of the car. Since the car is suspended in pendulum fashion with respect to the frame, relative motion between car and frame tends, generally, to permit the car to have less, and smoother, motion with respect to inertial space. Since a passenger senses only acceleration with respect to inertial space, such reduced action produces a more comfortable ride.
However, such a simple suspension without damping can produce, as a result of disturbances, car motions with respect to inertial space which repeat at the natural frequency of the system for extended periods. When using the pendulum-type mounting, the lateral movements of the car in the frame must thus be controlled so as to limit the amplitude and period of these movements, while at the same time softening their effect on the car and its riders. In the aforesaid British Pat. No. 1,407,158, rubber pads are disposed between the floor of the car and the frame, and are used to damp the lateral and vertical movements of the car in the frame.